Bronzing liquid



: Pat ented A g- 2 .1935. l i l I fBRONZ INGI JQUID l iogiinj and Waughnf 'gnors to Qomni erfcial Solvents Corpoy, Terri-Haida; I

ration, .T m "name, mu: aricprpomtion pr j N 0. Drawing. -zApplication January-18; V

,S r N -42 879 lbic al 7 (cl. e -"79) f JOur invention 1813136551170: improvements in bronzing zlacquers' havingaalmitrocellulosei base.

More.specifically,.ouriinventionirelates .to an im:

the,usual'.;defect.-of rapid gellingg: ii:Aabronzing."lacquers consists; essentiallyzof a suspension of .bronze..-powderf in a: nitrocellulose solution" or :ibronzingJliquidK. The usualxsolvent mixturestare 'empl'oyed'in these bronz ing liquids, and nitrocellulose-not the. high viscosity or .bronzing cottonf'. type isusually'used, although cotton of lower-Jviscosity: may also heiemployed;

proved type: of bronzinglacquer inotisubject to Gums and plasticizers are added'insom'e. cases" to improve the adhesion .of ;the :filnrto the; under surface, iand' .toimprove cits elasticity.;;;. 'he.bronze powder is usuallytnot added tothis mixture dur ing: its .prep'aratiom butyis. stirred into the, fill-7'- ished liquidojust before it; is desired ;to use-the lacquer. Ihe". reason for this procedureais i the tendency. of all abronzing.'zlacquerszto kform gels r short1y:aiter.= thefiiadmixturefofz the bronzeIpowr den 'lhejlifeof thellacquenze. g., the lengthof time before gelling occurs. depends uponsthecone centration and typeiiof bronzeiused -the grade of cotton; "the s'trengthzofthe; solventmizgture, and In general, however, geljqrmaother factors. tidn Etakesxplace fn-lessrthan tenfiifi'yz r and usually in; from-two. .hours to- -two.:days.;,w., Theentire lacquer ivvill gel: if; the bron e has remained. 1

pendemsbutcif it naslsettled the'sel fwilL-be formed only at the bottom-in the y of the bronze .powder; :This :gel; although. often. solui nalstrong-solvents-m.a t atment -qan s .disn ed by; urth r fl'fidi 9 the. usual so ver; mixture ,byva -m cha cal I Altho gh o; d uate. cx j am l has 'p e-f' viouny been offered "for" this "phenomenon; a

mbet r en ativ as n heyefby n r'e o i 'i iid t v ei Th i i i wi Off 9 agents to accomplish their purpc'mse is {evident from the fact that non e is in use at the-present time. Some; such asfsodium carbonate; not only have no" beneficial action but -have been fol'md V 0.05% of the total weight of thebronging liquid. l sne i -l amenc -stat e ,did not gel in most instances in LSiXfiYfd used contain esters, alcoholsliydrocarbons, and,

' vW e have now, ound the difficulties: zu eviolil s ly experienced may. be; overcomezby; using ias the z erful inhibiting agent, preventing gelling in cer- I tain cases if employedin-as small amounts as l l 0% of 1 acid," of'a' corresponding amounto the products -mentioned above will prevent g for considerable lengthsof time. -We have found in laboratory tests, using various types of bronzj: 15 ing liquidsand awide variety ofbronzes, t those iiij'which'0.4% la'cti'cacid was inc'prp l'ong'en 'and in no case in less thani'fi ft een The bronzin'g liquids containing no revents go t e o h r handsel d?!) W ayaii t g qi instances. 7

l'he bronzing lacquers in which lactic acid or other suitablelactic. acidderivatives can befsatisr factorily used a as the antiegel agent. maybe; 10: any-otthe usual types. .The nitrocellulosemav be the A; secondor 4 second.type,fon';ar highj viscosity cotton suchas 40.011170 seconds bronze ing'cotton. The usual plasticizers, such as di'- butyl phthalate, castoi" oil, or llndql may, be 'usedi Gums: such as dammar, ester ,gurn elemi, or synthetic resins may be incorporated-in he lacquers." 'Thebronze'powdenmaybefthe'v ous copper zinc alloys; mixtures of s'uch' powders, or... suchjpotwders w'itlr pigments or dyes-incor poratedinithem; These powders are usu 11y, mixe w nks-li tlethin er-andth na q 1 s finished bronzing liquid. The bronze is added proportions which may vary over a widerange, depending --upo-nthe particular "type w of: lacquer desired. For 100 parts of nitrocellulose, 10: to jl,-000--partsor more of bronze powder 'may b used: HoweverylOO -to200 parts are satisfactory for most purposes. Theso lvent mixtures usually if desired. carbonyl compounds orethers. Esters such asacetate, butylfaceta'teor butyl' pwnaearmm to acetone pr ia ew e f Qifid, an" t the mon et. u. e gb f fii m-Q to deleteriously afiect the composition as a whole.

7. A nitrocellulose bronzing lacquer containing an alkali salt of lactic acid in an amount sufiicient to prevent gelling of the composition and not sufiicient to deleteriously affect the composition as a whole.

8. A nitrocellulose bronzing lacquer containing as gel preventative 0.05% to 1.0% of a lactic 10 acid ester.

9. A nitrocellulose bronzing lacquer containing as gel preventative 0.05% to 1.0% of an aliphatic ester of lactic acid.

10. A nitrocellulose bronzing lacquer contain-' I ing as gel preventative 0.05%-1.0% of at least one material selected from the group consisting of lactic acid, esters of lactic acid,and salts of 

